//“传统的 JavaScript 类”Vehicle
function Vehicle() {
    this.engines = 1;
}
Vehicle.prototype.ignition = function () {
    console.log("Turning on my engine.");
};
Vehicle.prototype.drive = function () {
    this.ignition();
    console.log("Steering and moving forward!");
};
//“寄生类”Car
function Car() {
    // 首先，car 是一个 Vehicle
    var car = new Vehicle();
    // 接着我们对 car 进行定制
    car.wheels = 4;
    // 保存到 Vehicle::drive() 的特殊引用
    var vehDrive = car.drive;
    // 重写 Vehicle::drive()
    car.drive = function () {
        vehDrive.call(this);
        console.log(
            "Rolling on all " + this.wheels + " wheels!"
        );
    }
    return car;
}
var myCar = new Car();
myCar.drive();
    // 发动引擎。
    // 手握方向盘！
    // 全速前进!
